Iran does not even have nuclear weapons but if it tests long range missiles that is bad it might be a threat to Israel. Of course it is OK for Israel to threaten to attack Iran and it has nuclear weapons already although it is usually not polite to point out that fact.
North Korea has nuclear weapons but a test of a long range missile was a great provocation even though the test failed. But now India which has nuclear weapons also tests a long range missile that can carry such weapons and target Chinese cities. The test is a success and certainly in the U.S. there is no outcry at the spread of nuclear weapons or the means of their delivery. This is because to the U.S. these weapons are benign at least for the present while India is an ally.
The U.S. was not always so tolerant of India. In 1974 when India first tested a nuclear weapon the US. imposed sanctions for a full 25 years. But now the U.S. sees India as a check against Chinese influence in Southeast Asia so now the test of a missile that could carry nuclear weapons is a plus. The U.S. and others have traded nuclear materials with India since 2008 in violation of the NPT (Non-proliferation treaty). For more see this article.