led forces sent to Bahrain to help crush anti-government protests will remain even after emergency rule is lifted next month, the head of the kingdom's military said in a move that is likely to deepen regional tensions with Iran. Iran has condemned the 1,500-strong Gulf Arab force in Bahrain. In response, Gulf leaders have sharply warned Iran to stay out of their affairs and accused Bahrain's protesters of having links to groups such as the Iranian-backed Hezbollah militants in Lebanon. The Bahrain military commander, Sheikh Khalifa Bin Ahmed Al-Khalifa, also threatened even harsher crackdowns if demonstrators return to the streets in the strategic US ally, which is home to the Navy's 5th Fleet. “I say to those who did not get the message, `If you return we will come back, stronger this time,”' Sheikh Ahmed was quoted as saying late Wednesday by the official Bahrain News Agency. He further claimed that protesters were “given pills which affected their minds and made them do unusual things” — a new allegation that echoed assertions by Libyan leader Muammar Gaddafi that his opponents included young people on hallucinogenic pills placed “in their coffee with milk, like Nescafe.” Meanwhile, the expected resumption of a trial against 21 opposition leaders and human rights activists was adjourned until May 16. The activists are accused of plotting against the state and having links to foreign factions — an apparent reference to Hezbollah. Fourteen of the suspects are in custody and the rest are being tried in absentia in a special security court set up under martial law-style rule imposed in March. Separately, the same court also convicted another opposition supporter on charges of attempted murder of a police officer and participation in a protest aimed at disrupting public order, a report by the state-run Bahrain News Agency said Thursday. It added that the protester, Hamad Yousef Kazim, was sentenced to 15 years in prison. Kazim's court-appointed lawyer can appeal the sentence, the report also said. Bahrain's king said the emergency rule will be lifted June 1. But the military chief's statements suggest a heavy security presence will remain along with the troops. At least 30 people have been killed since the protests began in February. Bahrain has said it will try five prison guards over the death in police custody of a activist during protests. The guards' arrests and trial were reported by the Bahraini news agency BNA late Wednesday as Bahrain prepared to lift martial law imposed during weeks of pro-democracy protests.