Updated

Thanks to Mitt Romney's overseas trip, foreign policy has had an airing in a presidential campaign dominated, as usual, by matters at home. For all the words on both sides, though, it can be difficult in the end to see how President Barack Obama and his Republican challenger differ on what they would do.

Some contrasts may turn out to be consequential, considering Romney's seemingly harder line on Iran, Russia and more. Others may be overtaken, as foreign policy often is, by developments abroad that no one can predict and by the tendency of U.S. politicians to see national security interests in a less divisive light than domestic affairs when the time comes to act.

A synopsis of their positions on a selection of foreign policy issues:

IRAN

Both say Iran cannot be allowed to gain the capability to build nuclear weapons.

Obama opposes a near-term military strike on Iran, either by the U.S. or by Israel, to sabotage nuclear facilities that could be misused to produce a nuclear weapon, preferring sanctions and negotiation for now. But he reserves the right to conclude that only a military strike can stop Iran from getting the bomb. Romney appears to present Iran as a clearer U.S. military threat and has spoken in more permissive terms about Israel's right to act, without explicitly approving of such a step. "Of course you take military action" if sanctions and internal opposition fail to dissuade Tehran from making a nuclear weapon, he has said.

AFGHANISTAN

Obama and Romney are on the same page in planning for an end to combat operations in 2014, the likely outcome no matter who wins in November.

Romney has quarreled with the pace and scope of the withdrawal since early in the GOP primary campaign while recently making clear his endorsement of the 2014 end point. He says, though, he would ultimately be guided by conditions on the ground and the advice of commanders, perhaps making his deadline softer than Obama's. But the president, too, is capable of adapting to developments in Afghanistan. The bottom line is that, barring an extraordinary turn of events, neither candidate has the taste to carry on the war beyond 2014.

RUSSIA

Romney has branded Russia the "No. 1 geopolitical foe" of the U.S., drawing a rhetorical line at odds with Obama's effort to improve relations that deteriorated in the previous administration. What this distinction means in practice is uncertain.

Obama's work to improve US-Russia relations — the administration's cliche is to "reset" them — has been overlaid with new tensions, over Syria and more, as well as some successes, such as the negotiation of the New START agreement reducing nuclear arsenals in both countries.

Romney pledges to review that agreement, although actually backing out is almost unimaginable, and he says he would help Central Asian and European states become less dependent on Russian energy as a way to check Moscow's expansionist behavior. He also proposes encouraging civil-society exchanges with Russians to counter increasingly "authoritarian" practices of the government. The Obama White House, too, has voiced worry about a backtracking of democracy in Russia and sharply criticized a new law requiring non-governmental groups that get foreign money and engage in political activity to register as foreign agents.

SYRIA

Both candidates say President Bashar Assad must leave power. Both stop short of committing U.S. forces to making him go.

Obama declined to repeat the Libya air power commitment for the Syrian opposition, instead seeking to build international consensus toward the goal of persuading Assad to leave and to press Russia and China to stop shielding his government from international sanctions. The Obama administration placed financial sanctions on many top members of the Syrian government as an additional pressure tactic. Romney has spoken in favor of covert action by the U.S. and regional allies in Syria while saying "the right course is not military" intervention by the U.S.

ISRAEL

Romney has aligned himself closely with Israeli Prime Minister Benjamin Netanyahu and sought to exploit the sense that relations with Israel are shaky under Obama. He pledges more military assistance to Israel and agreed with Israel's position that Jerusalem is Israel's capital, disregarding the Palestinians' claim to the eastern sector, annexed by Israel in 1967 in a move that is not internationally recognized. This contrasts with U.S. policy that the city's designation is a matter for negotiation between the Jewish state and Palestinians. But Romney has not committed to moving the U.S. Embassy from Tel Aviv, saying only that he is open to that.

Obama has chastised Israel for continuing to build housing settlements in disputed areas and has pressed both sides to begin a new round of peace talks based on the land borders established after the 1967 Arab-Israeli conflict. He's also signed a law to expand military and civilian cooperation with Israel. The law affirms U.S. support for negotiating the establishment of a Palestinian state, reflecting a bipartisan consensus in the U.S.

CHINA

Romney says he would brand China as a currency manipulator, a step that could lead to broad trade sanctions if talks did not resolve the dispute. A country's artificially low currency can give it a disproportionate trade advantage by making its exports cheaper. Obama has refused to cite China for currency manipulation, fearing a trade war, instead pressing China diplomatically to lets its currency rise. But his administration has aggressively brought unfair-trade cases against China to the World Trade Organization.

Romney also proposes more military capabilities in the Pacific to challenge Beijing's growing influence in East Asia.