Secretary of State John F. Kerry on Thursday called on Iran to stop its destabilizing behavior and work with its neighbors in the Middle East to end the wars in Yemen and Syria.

Kerry, who came to the island kingdom of Bahrain to meet with his counterparts in the Gulf Cooperation Council, said they all were concerned about Iran. Last week, a U.S. Navy ship stopped a small ship and seized hundreds of AK-47 assault rifles, rocket-propelled-grenade launchers and machine guns that Kerry said were on the move from Iran to arm Houthi rebels in Yemen.

“Rather than send weapons to the Houthis, join in efforts to convince the Houthis to make peace,” Kerry said.

U.S. officials are concerned about the fragility of an existing cease-fire in Syria and have expressed uncertainty over the prospects for a cease-fire that is due to start this weekend in Yemen. Kerry said he and the foreign ministers of Arab states in the Persian Gulf were in the early stages of assessing whether a partnership between NATO and the six GCC nations would contribute to regional security.

[The tragic story of a dead baby shows the terrible toll of Yemen’s war]

Saudi Arabia is leading a coalition of gulf countries conducting airstrikes against the Iranian-backed Houthis. Saudi Foreign Minister Adel al-Jubeir, whose country chairs the GCC, said relations with Iran will be chilly until the country ends its interventionist policies.

“We stressed that if Iran wants to have normal relations with the GCC states, it has to change its policies and abide by the good-neighborhood principle,” he said.

Iranian President Hassan Rouhani has made overtures for warmer relations, efforts that powerful segments of the Iranian government do not support.

“Tehran wants interaction with the world, with its neighboring countries,” Rouhani told a gathering in Tehran aired live Thursday on state TV.

The criticism of Iran emanating from the gulf came as ships in the U.S. Navy’s Fifth Fleet, which is based in Bahrain, joined in a three-week, multinational exercise to practice mine clearing and other tactics designed to keep open the sea lanes through which at least a third of the world’s oil resources are shipped. At least four ships thought to be bound from Iran to Yemen have been stopped in the past six months, and large quantities of weapons were seized.

[Navy investigation into how U.S. sailors were detained by Iran reaches top admirals]

“If Iran is going to give meaning to the words in the last few days about wanting to work with people, it is by getting engaged in making peace in Yemen, not adding more weapons and fueling the conflict,” Kerry said.

Referring to Bahrain earlier in the day, Kerry criticized the Bahraini opposition, saying its boycott of a 2014 election had a “polarizing” effect.

Kerry, appearing with Bahraini Foreign Minister Sheik Khalid bin Ahmed al-Khalifa, praised reforms Bahrain has made to open its political system but said more steps were needed to counter violent extremism. He suggested that the opposition had played a role in preventing more reforms.

“Regrettably, I think a great mistake was made when the opposition chose to boycott an election,” said Kerry, the first U.S. secretary of state to visit Bahrain since a government crackdown that followed protests in 2011 by Bahrain’s majority Shiite Muslims. “I think that polarizes things rather than helps them.”

[One family pays a heavy price for demanding democracy in Bahrain]

Standing beside the foreign minister, Kerry hailed Bahrain as a “critical security partner” of the United States and said security was the foundation of the relationship between the countries.

“At the end, our relation with Bahrain is built on common interests that we share, and one of those interests is joint efforts to combat violent extremism,” Kerry said. “We believe that broadening rights and opportunities, bringing people together in the political process, is one of the ways to counter it.”

International human rights groups have criticized the Bahraini government since a security clampdown on protesters demanding reforms and a greater voice in the governing of the kingdom, which is led by Sunni Muslim rulers. Human Rights Watch says there has been little meaningful progress in reforms since then, and it accused the government of pressuring the opposition by detaining activists.

In one of the most recent cases, activist Zainab al-Khawaja, the daughter of a well-known human rights activist serving a life sentence for his role in anti-government demonstrations, was imprisoned after she tore up a photo of the king. She took her 15-month-old son to jail with her.

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