Dictionary.com
Thesaurus.com

well-defended

British  

adjective

  1. having sufficient defences against attack

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

These would be "a small number of conventionally-armed ballistic missiles over well-defended airspace... and they're quite inaccurate at very long ranges".

From BBC

This kind of conflict might also bring in a range of ‘softer’ and less well-defended targets than the nine U.S. military bases across the Middle East, which together hold an estimated 30,000-40,000 troops, as well as ‘Fortress Israel’.

From Barron's

This kind of conflict might also bring in a range of ‘softer’ and less well-defended targets than the nine U.S. military bases across the Middle East, which together hold an estimated 30,000-40,000 troops, as well as ‘Fortress Israel’.

From Barron's

It could muster only a missile barrage against a well-defended U.S. base in Qatar.

From The Wall Street Journal

Yet hackers linked to its biggest adversary, Iran, have managed to pull off a series of successful breaches by using known vulnerabilities to attack institutions that aren’t as well-defended as the country’s critical infrastructure.

From The Wall Street Journal