Defense Secretary Chuck Hagel pledged more non-lethal U.S. aid to Ukraine's military Thursday while sidestepping a decision on Poland's call for "American boots on Polish ground."

Hagel spoke at the Pentagon as negotiators in Geneva agreed on a joint statement for defusing the crisis that Secretary of State John Kerry said could "open the door" to a settlement of the rift between Russian-speaking eastern Ukraine and the Kiev government.

Hagel said the U.S. would send medical supplies, helmets, water purification units, sleeping mats and generators to Ukraine to counter what he called Russia's "ongoing de-stabilizing activities in eastern Ukraine."

Hagel echoed frequent Pentagon statements in recent weeks that Ukraine's urgent request for weapons and intelligence support was still under consideration but he gave no timeline for a decision.

Hagel backed the recommendations of Air Force Gen. Philip Breedlove, NATO's Supreme Commander, for increased air and sea patrols by the alliance and for more joint exercises that would put U.S. and NATO forces in Eastern Europe on a rotational basis.

However, Hagel would not commit to Poland's request for the U.S. and NATO to establish permanent bases in Poland and other alliance states in Eastern Europe.

"We're assessing what additional contributions we can make," Hagel said at a Pentagon briefing with Polish Defense MInister Tomasz Siemoniak. "No decisions have been made."

"We have to be alert to all possibilities," he said. "The actions of the Russians over the last two months are not only irresponsible, with violating the territorial integrity of a sovereign nation, they're dangerously irresponsible."

NATO's role was to look at every possibility to deter Russian aggression, Hagel said.

Siemenowiak cited Poland's long history of confrontation with Russia in stating that Warsaw's main foreign policy goal was simple.

"We want to be as close to the West as possible. There is no other way for us to guarantee our own security," said Siemoniak, who was accompanied to Washington by Lt. Gen. Mieczyslaw Gocul, chief of Poland's General Staff.

"Poland is very much interested in increasing the allied American presence in Poland," Siemoniak said. In an interview Wednesday with Defense News, Siemoniak said that a U.S. Army presence "or (an) Army base would be a very visible testimony to the American boots on the Polish ground."

The Pentagon briefing came amid reports of the bloodiest clashes yet between Ukrainian forces and armed separatists, and Russian President Vladimir Putin's declaration that he would be justified in ordering an invasion of Ukraine.

"I really hope that I do not have to exercise this right," Putin said in televised comments, "and that through political and diplomatic means we will be able to solve the most acute problems in Ukraine today."

Putin noted that he had been authorized by Russia's parliament in early March to use force in Ukraine if necessary to protect Russian-speaking areas of eastern Ukraine. Putin also denied that Russian intelligence and special operations units were in Ukraine to direct and support the separatists.

"It's all nonsense," Putin said.

In Geneva, the new government in Kiev was engaging in its first direct talks with Moscow at a meeting involving Kerry, Russian Foreign Minister Sergei Lavrov, European Union foreign policy chief Catherine Ashton and acting Ukrainian Foreign Minister Andrii Deshchytsia.

"The Geneva meeting on the situation in Ukraine agreed on initial concrete steps to de-escalate tensions and restore security for all citizens," according to a joint statement issued at the conclusion of the talks. "All sides must refrain from any violence, intimidation or provocative actions."

Kerry later said that the U.S. was ready to impose tougher economic sanctions on Russia "if we don't see movement in the right direction."

The joint statement in Geneva came after reports that Ukrainian National Guardsmen in the southeastern city of Mariupol shot and killed three militants and wounded at least 13 others when a pro-Russian armed group tried to take over their military base.

"Together with a special Interior Ministry unit, the Ukrainian forces dispersed most of the crowd of 300, arresting 63. The core of the group was corralled and the militant crowd was broken up," the Kiev Post newspaper reported.

Ukraine's ambassador to the U.S., Olexandr Motsyk, accused Moscow of "sticking to the same routine" in eastern Ukraine that was used in the takeover of Crimea.

"Ukraine is fighting back," Motsyk said in a Washington Post op-ed. "It cannot allow the Russian-equipped, Russian-paid and Russian-deployed special ops units to spread fear among Ukrainians."

Motsyk's statements were echoed by Samantha Power, the U.S. ambassador to the United Nations.

Addressing the Security Council Wednesday night, Power said: "Let us be clear, the actions the world witnessed in Crimea – and the denials of Russian involvement in the lead-up to its illegal annexation and occupation – are repeating themselves in eastern Ukraine."

-- Richard Sisk can be reached at richard.sisk@monster.com