Express.co.uk readers can vote in our poll on who is the greatest threat to the West out of the four countries. China has sparked controversy after imposing a much-criticised national security law on Hong Kong.
Boris Johnson accused Beijing of a “clear and serious breach” of its treaty with Britain when the territory was handed back to China in 1997.
The UK is pushing forward with its plan to give three million Hong Kong residents the right to settle in Britain, prompting China to warn of retaliation.
The draconian new security law – which came into effect on Tuesday night – makes activities deemed subversive or secessionist punishable by imprisonment.
Meanwhile, China rejected criticism by the US over its plan to hold military exercises in the South China Sea.
The US Defense Department warned in a statement on Thursday that the provocative move was “counter-productive to efforts at easing tensions and maintaining stability”.
China announced last week it was holding five days of drills starting on July 1 near the Paracel Islands, which are claimed by both Beijing and Vietnam.
Elsewhere, denuclearisation talks between North Korea and the US are at a deadlock.
Tensions between North Korea and South Korea reached boiling point last month when Kim Jong-un blew up a joint liaison office which was built in a bid to improve ties between the two Koreas.
The pair met again at the demilitarized zone between the two Koreas later that year but no progress has been made.
It comes as Iran continues to roll back on its commitments to the 2015 nuclear deal with six world powers including the UK.
Tehran agreed to limit its nuclear activities in return for relief of crippling sanctions.
But Iran has rolled back on its commitments to the deal since Mr Trump pulled out in 2018 and reimposed sanctions, with the US President branding the agreement “decaying and rotten” and “defective to its core”.