Three persons have been killed after two small planes collided mid-air in the US state of Florida, authorities have said.

The accident took place on Tuesday, the Federal Aviation Administration said. The whereabouts of a possible fourth passenger is still unknown, Xinhua news agency reported.

Police in the US have confirmed that the man shot dead in a shootout in Kansas City was the suspect in the killing of Indian student Sharat Koppu, who was from Telangana.

US President Donald Trump is facing a barrage of criticism for defending his Russian counterpart Vladimir Putin over claims of Moscow's interference in the 2016 presidential elections.

At a joint news conference with Putin following their summit in Finland on Monday, Trump refused to denounce the Russian leader for interfering in the presidential campaign and instead contradicted American intelligence agencies, the US media reported on Tuesday.

 Five soldiers were killed and one was injured in a military helicopter crash on Tuesday in South Korea's Pohang city, authorities said.

The chopper crashed at the landing strip of a military unit in Pohang, South Gyeongsang province, at about 4.45 p.m., Xinhua news agency reported.

China has installed an unmanned automatic weather observation station near its border with India in Tibet to support its Army in the event of a live fire conflict with New Delhi.

At least 62 militants were killed in airstrikes in Afghanistan's Kandahar province, a military official said on Tuesday.

"The Army aircraft targeted Taliban hideouts in Maroof district in the past 24 hours during which the militants including a key commander were killed," the official told Xinhua news agency.

Iranian Minister of Petroleum Bijan Namdar Zanganeh said Monday that the Organization of the Petroleum Exporting Countries (OPEC) would suffer if its members do not adhere to their commitment regarding the oil output.

The US is currently facing a serious shortage of airline pilots, particularly at the regional airline levels, according to a report.

The Federal Aviation Administration said in the report on Monday that there were about 827,000 pilots in America in 1987. Over the past three decades, that number decreased by 30 per cent, reports CNN.