It is Iran's missile armaments that pose the greatest concern for American forces in the Gulf, especially for the US Navy.
1	It	it	PRON	PRP	Case=Nom|Gender=Neut|Number=Sing|Person=3|PronType=Prs	6	expl	6:expl	_
2	is	be	AUX	VBZ	Mood=Ind|Number=Sing|Person=3|Tense=Pres|VerbForm=Fin	6	cop	6:cop	_
3-4	Iran's	_	_	_	_	_	_	_	_
3	Iran	Iran	PROPN	NNP	Number=Sing	6	nmod:poss	6:nmod:poss	_
4	's	's	PART	POS	_	3	case	3:case	_
5	missile	missile	NOUN	NN	Number=Sing	6	compound	6:compound	_
6	armaments	armament	NOUN	NNS	Number=Plur	0	root	0:root|8:nsubj	_
7	that	that	PRON	WDT	PronType=Rel	8	nsubj	6:ref	_
8	pose	pose	VERB	VBP	Mood=Ind|Number=Plur|Person=3|Tense=Pres|VerbForm=Fin	6	advcl:relcl	6:advcl:relcl	_
9	the	the	DET	DT	Definite=Def|PronType=Art	11	det	11:det	_
10	greatest	great	ADJ	JJS	Degree=Sup	11	amod	11:amod	_
11	concern	concern	NOUN	NN	Number=Sing	8	obj	8:obj	_
12	for	for	ADP	IN	_	14	case	14:case	_
13	American	American	ADJ	JJ	Degree=Pos	14	amod	14:amod	_
14	forces	force	NOUN	NNS	Number=Plur	11	nmod	11:nmod:for	_
15	in	in	ADP	IN	_	17	case	17:case	_
16	the	the	DET	DT	Definite=Def|PronType=Art	17	det	17:det	_
17	Gulf	gulf	NOUN	NN	Number=Sing	14	nmod	14:nmod:in	SpaceAfter=No
18	,	,	PUNCT	,	_	14	punct	14:punct	_
19	especially	especially	ADV	RB	_	23	advmod	23:advmod	_
20	for	for	ADP	IN	_	23	case	23:case	_
21	the	the	DET	DT	Definite=Def|PronType=Art	23	det	23:det	_
22	US	US	PROPN	NNP	Number=Sing	23	compound	23:compound	_
23	Navy	Navy	PROPN	NNP	Number=Sing	14	nmod	14:nmod:for	SpaceAfter=No
24	.	.	PUNCT	.	_	6	punct	6:punct	_
