In a bold speech clearly aimed at Western negotiators and Iran's moderate political wing, Supreme Leader Ayatollah Ali Khamenei declared Wednesday his rogue nation would remain strong through its missile program -- not through talks with other countries.

"Those who say the future is in negotiations, not in missiles, are either ignorant or traitors," Iran's spiritual leader said in a speech carried on his website.

Earlier this month, Iran's Revolutionary Guard reportedly test-fired two ballistic missiles with the phrase "Israel must be wiped out" written in Hebrew on them, the latest in a string of missile tests that violated a United Nations Security Council resolution supporting the nuclear deal reached by Iran, the U.S. and other western nations. The launch happened while Vice President Joe Biden was visiting Israel.

The much-publicized deal aims to ease sanctions on Iran in exchange for the scaling back of its nuclear program. Secretary of State John Kerry told MSNBC in January that U.S. allies in Israel were safer as a result of the deal, adding, "The world is safer today."

Kerry said two weeks ago that the latest Iran missile tests "could invite additional sanctions as we put them in place."

Iran's lead negotiators for the deal were moderate president Hassan Rouhani and his administration -- not the ayatollah.

"If the Islamic Republic seeks negotiations but has no defensive power, it would have to back down against threats from any weak country," Khamenei said Wednesday.

There was no immediate reaction from the State Department. After the latest test-launches, State Department spokesman John Kirby vowed to bring them to the attention of the United Nations Security Council, saying, “We’re not going to turn a blind eye to this and we’re not at all trying to make any excuses for it.”

Khamenei's speech may have been sparked by a tweet from moderate former president Akbar Hashemi Rafsanjani who claimed, "the future is in dialogue, not missiles," according to Reuters.

Hard-liners in Iran's military have fired rockets and missiles despite U.S. objections since the deal, and have shown underground missile bases on state television. They insist their nuclear program is for peaceful purposes only.

In October, Iran successfully test-fired a new guided long-range ballistic surface-to-surface missile. It was the first such test since Iran and world powers reached the landmark deal last summer.

U.N. experts said the launch used ballistic missile technology banned under a Security Council resolution. In January, the U.S. imposed new sanctions on individuals and entities linked to the ballistic missile program.

Iran also has fired rockets near U.S. warships and flown an unarmed drone over an American aircraft carrier in recent months.

In January, Iran seized 10 U.S. sailors in the Gulf when their two riverine command boats headed from Kuwait to Bahrain ended up in Iranian territorial waters after the crews "misnavigated," the U.S. military said. The sailors were taken to a small port facility on Farsi Island, held for about 15 hours and released after Kerry spoke several times with Iranian Foreign Minister Mohammad Javad Zarif.

The Associated Press contributed to this report.